Cardiac pacing electrically stimulates the heart when the heart's natural pacemaker and/or conduction system fails to provide synchronized atrial and ventricular contractions at appropriate rates and intervals for a patient's needs. Such bradycardia pacing provides relief from symptoms and even life support for hundreds of thousands of patients. Cardiac pacing may also give electrical overdrive stimulation intended to suppress or convert tachyarrhythmias, again supplying relief from symptoms and preventing or terminating arrhythmias that could lead to sudden cardiac death.
Cardiac pacing is typically performed by a pulse generator implanted subcutaneously or sub-muscularly in or near a patient's pectoral region. The generator usually connects to the proximal end of one or more implanted leads, the distal end of which contains one or more electrodes for positioning adjacent to the inside or outside wall of a cardiac chamber. The leads have an insulated electrical conductor or conductors for connecting the pulse generator to electrodes in the heart. Such electrode leads typically have lengths of 50 to 70 centimeters.
Although more than one hundred thousand conventional cardiac pacing systems are implanted annually, several well-known difficulties exist. For example, a pulse generator, when located subcutaneously, presents a bulge in the skin that patients can find unsightly or unpleasant. Although sub-muscular or abdominal placement can address some concerns, such placement involves a more difficult surgical procedure for implantation and adjustment, which can prolong patient recovery. Further, the lead body can be cut inadvertently during surgery by a tool, or cut after surgery by repeated stress on a ligature used to hold the lead body in position. Moreover, repeated movement for hundreds of millions of cardiac cycles can cause lead conductor breakage or insulation damage anywhere along the lead body.
Many of the issues associated with conventional pacemakers are resolved by the development of a self-contained and self-sustainable pacemaker, or so-called leadless pacemaker, as described herein.